He has not played in a game since he felt tightness in his hamstring one week ago. Cubs manager Dale Sveum said Castro may not be back in a game until Monday.

"I want to be playing," Castro said. "I don't want to see the other people play. It's not for me. I like to play every time I can get in the game."

If there's no pain, why is he sitting now?

"I want to be strong, I don't want to go in a game now and get hurt in a game and [be] out maybe one month of the season, two weeks," he said. "I don't want that. I want to make sure I'm good and can play in the season."

Castro appeared in all 162 games last season, and that's a goal of his heading into the 2013 season.

"It's an important goal for me," he said. "I see guys who play a lot of games, and that's what I like to play. I don't care where, I don't care what league, I like to play. This is the only thing I know how to do is play baseball. That's why I put it in my mind to play. I don't want to miss games. In the season, I don't want to miss games. I like to play every game."